2545: With a twist

41 (four words) suggests the other unclued lights – which are individual examples (not group names) of a kind – and how they must be entered in the grid. All answers are in Chambers.

Across

8 American twice rejected West African (4)

11 Like some plants you’d set in cold ground without oxygen (14)

12 One’s fired head dismissed from private school (5)

14 Insect-eating rodent moving lightly (7)

16 On the job, one way or another (4, two words)

21 No good place for putting ditch (4)

22 Noble king left to appear later (4)

23 Titans of...